Introduce new flask based python backend

This supports most functionality. Tested the following functionality:
* Create account
* Delete account
* Create a card
* Download offline copy (couldn't log in) - needs work
* Change passphrase
* One time password creation and use

scripts/builder/frontends/deltaBuilder.py

@@ -1,5 +1,5 @@
 from frontendBuilder import FrontendBuilder
-from scss import Scss
+#from scss import Scss
 
 import os
 import shutil
@@ -38,6 +38,7 @@ class DeltaBuilder(FrontendBuilder):
 		return ""
 
 	def preprocessCSS (self, targetFile):
+		from scss import Scss
 		logging.basicConfig()
 		scssVariables = {}
 		scssCompiler = Scss(